Well, yes, inertia and symbolic action. But why don't you have to take them off before entering a high speed train? https://transweb.sjsu.edu/research/SP0520-

Well, yes, inertia and symbolic action. But why don't you have to take them off before entering a high speed train? https://transweb.sjsu.edu/research/SP0520-Terrorist-Attacks-Passenger-Rail-Transportation https://transweb.sjsu.edu/research/SP0520-Terrorist-Attacks-...